Tropical cyclones are
classified into three main groups: tropical depressions, tropical
storms, and a third group whose name depends on the region. A
tropical depression is an organized system of clouds and thunderstorms
with a defined surface circulation and maximum sustained winds
of less than 17 metres per second (33 knots, 38 mph, or 62 km/h).
It has no eye, and does not typically have the spiral shape of
more powerful storms. A tropical storm is an organized system
of strong thunderstorms with a defined surface circulation and
maximum sustained winds between 17 and 33 meters per second (34
to 63 knots, 39 to 73 mph, or 62 to 117 km/h). At this point,
the distinctive cyclonic shape starts to develop, though an eye
is usually not present.

Hurricanes are
categorized on a 1-to-5 scale according to the strength of their
winds, using the Saffir-Simpson Hurricane Scale. A Category 1
storm has the lowest wind speeds, while a Category 5 hurricane
has the strongest. These are relative terms, because lower category
storms can sometimes inflict greater damage than higher category
storms, depending on where they strike and the particular hazards
they bring. In fact, tropical storms can also produce significant
damage and loss of life, mainly due to flooding. The U.S. National
Hurricane Center classifies hurricanes of Category 3 or above
as Major Hurricanes. The Joint Typhoon Warning Center classifies
typhoons with wind speeds of at least 150 mi/h (67 m/s or 241
km/h; a strong Category 4 storm) as Super Typhoons.
Above Images Are From The NOAA